I have the exact same issue with my Dell Inspiron 15 laptop. It started around a year ago, and like you, I have not dropped or damaged the computer in any way.

The delamination is spreading along the bottom of the screen and moving upwards.

Has anybody received a reply from Dell on this issue?

Yes happened to me

I own a Dell Latitude E7240 with a touch screen and I think I have this same de-lamination issue. My screen has become discolored and its spreading in from the corners and sides. From other posts it looks like this could be a recurring problem with certain Dell touch screens. Unfortunately my laptop is a few years old and out of warranty but I would be interested to see if anyone has had any luck getting Dell to replace their screen.

I'm having the same issue on my laptop:  Latitude E7240 with 1080p touchscreen.  It started out of no-where.  It is spreading.  I contacted Dell.  May laptop is out of warranty.  They offered for me to send it in for diagnostics for a fee and then whatever it costs to fix.  I inquired about them selling me a replacement screen.  They will sell me a re-furbed screen only.  I do not know if any new ones are available.  I think I will look into a compatible replacement screen by another manufacturer.  Definitely some sort of manufacturing defect.  It's too bad that it happened to me past warranty.  A search on the internet appears to show this has happened quite a bit.

I have the same exact issue with my Dell Latitude E7250. It gets worse and worse by each day. It is really a shame that there isn't a recall or replacement campaign because it seems like a common issue with these units. 

Mine has a very bright corner, looks like some kind of delamination too.  Started today, also on my E7250!  Same day that Rocket posted too!!  
My laptop barely gets moved, and has been fine until I saw this.

I posted a year ago about a delamination issue on my E7240. Initially I got the following automated response from Dell

"Hello, I’m your Dell virtual assistant. In case you have a question about your Dell system or need technical assistance, may I have the Service Tag or Express Service Code or order number, please? I’ll validate your system warranty and get back to you with the available options."

My laptop was a few years old and well beyond the warranty period so I did not reply. Along with various other posts and similar screen problems shown on ebay I suspect this is a fairly common issue and must be known to Dell who have obviously decided to ignore the problem. I've also noticed a sticky liquid leaking out of one corner of the screen which I assume is coming from the screen.  Once again if you google “Dell screen leaking” you will find many other instances including other posts on this board.

I was only motivated to write this follow up because over the last year my screen has got progressively worse and now shows nothing except a random pattern of stripes and blotches (see attached pictures). Fortunately I can still use my laptop with an external monitor via the hdmi or display port but using it way from my desk is no longer possible. With Windows 11 due soon I am looking for a more modern replacement but needless to say Dell will not be on my shortlist.

20202021

After my post above I got a message from DELL-Cares who again requested my service tag and then again confirmed my warranty has expired which was not helpful. Its ironic I got a reply from DELL-Cares when clearly they don't. These screens were defective from the start and yet Dell refuse to take any responsibility.

Just to add to the list, my E7270 seems to have just developed delamination - I assume that's what it is?  Here's a photo - hard to capture and it looks worse in real life, but it's across the top of the screen:

My laptop is well outside the warranty period too, but I don't think it's reasonable to expect this issue.  Not sure if it's a Dell or a touchscreen issue generally.

Just to be safe, I think I'll avoid Dell AND touchscreens for my next laptop!

It seems that replacement screens are unobtainable - and the connectivity requires a like for like replacement.  Not sure another touchscreen is such a great idea!

As a matter of interest, can anyone suggest whether the issue will get worse and whether the screen actually gets unreadable, and over what likely timescale?

Sorry we're all in a club we really don't want to be in!

Pete